1. Field of the Invention
The present invention relates to a recording medium clamping apparatus, and more particularly to a clamping apparatus used in an apparatus for recording and/or reproducing on a disc-shaped recording medium such as a magnetic disc for clamping a recording medium on a rotating spindle.
2. Description of the Prior Art
As an example of a conventional type of clamping apparatus is known an arrangement such as shown in FIGS. 1A and 1B.
In FIGS. 1A and 1B, reference numeral 1 denotes a base of a magnetic disc recording and/or reproducing apparatus. Reference numeral 2 denotes a spindle for driving rotatingly a magnetic disc 10 which is a recording medium. Reference numeral 3 denotes an upper plate member as an insertion guide for guiding a jacket 10' that accommodates a magnetic disc 10 on the base 1. Reference numeral 4 denotes a center cone as a clamping means to position the center portion of the magnetic disc 10 on the spindle 2 and clamp the magnetic disc 10 with the spindle. Reference numeral 5 denotes a clamp operating plate which supports rotatably the center cone 4 near its top end 5a. Reference numeral 6 denotes a cam which is in contact with the plate 5 near its base portion 5b so as to cause the plate to swing. Reference numeral 7 denotes a shaft linking an operating lever (not shown) to the cam 6. Reference numeral 8 denotes a leaf spring supporting the plate 5 at its base portion and exerting a return force pushing the plate upwards. Reference numeral 9 denotes an attaching screw for fixing the leaf spring 8 to the base 1.
FIGS. 1A and 1B show the condition when the magnetic disk 10 is not clamped and the condition when the magnetic disc 10 is clamped, respectively.
In the unclamped condition shown in FIG. 1A, when the operating lever (not shown) rotates the cam 6 in the direction of an arrow A, the plate 5 is pushed downwards, so that the center cone 4 which is supported by the plate 5 traces an arc and moves into the center opening of the magnetic disc 10 and into a recess 2a on the spindle 2. Then, the magnetic disc 10 is positioned and clamped. When the cam 6 has rotated through approximately 90 degrees, the clamping action is completed, thereby producing the condition shown in FIG. 1B.
In conventional clamping apparatus, however, the plate 5 is supported at one end by a leaf spring 8 and is arranged so as to move through an arc, so that when the magnetic disc 10 is not clamped, that is, in the condition shown in FIG. 1A, the end 5a is in an extremely high position. This influences the overall thickness of the recording and/or reproducing apparatus, and prevents a slim design of such an apparatus.